Gallstones are a common problem in the United States and the most frequent cause of gallbladder inflammation. Calculi in other parts of the biliary system are also common place as are calculi in the urinary system. Several percutaneous and open surgical procedures are available for removing calculi from the biliary or the urinary system. With respect to the biliary system, one invasive, open surgical procedure is known as cholecystectomy or choledocholithotomy in which the gallbladder is removed along with any stones from the common duct. A T tube is commonly inserted in the duct for removal of residual calculi. However, this procedure is, as are other open surgical procedures, subject to an extensive recovery period lasting anywhere from two to six weeks.
Minimally invasive surgical procedures that utilize percutaneous access include, for example, a percutaneous cholecystolithotomy in which calculi are removed from the gallbladder through a percutaneously inserted access sheath. Several postoperative access routes such as transcholedochal, transcystic, and transcholecystic are employed for removing biliary stones from the gallbladder, cystic duct, or common duct. In such cases, the extractions are carried out through the fistula tract left by a T tube. The percutaneous extraction is based on the use of forceps or basket-tipped catheters. Forceps enable a quick extraction of stones within reach. Furthermore, forceps facilitate crushing large-sized stones and extracting compacted stones. One problem with forceps is that they cannot negotiate double or triple curves or the exaggerated tortuosities of fistula tracks. This problem is partially overcome with the basket-tipped catheter to overcome such winding courses, but it is frequently not possible to seize the large-sized or impacted stones.
A problem with most basket-tipped catheters or stone retrieval baskets arises in the case of very small or flat stones or when the stones lie in large cavities where they have ample room for displacement. Most stone extraction baskets are of the helically shaped variety for permitting entry of the stone only from the side of the basket. This is because the tip of the basket, which usually contains a small length of cannula or a fastener for holding the ends of the wire basket together, is too sharp and inefficient for a head-on or an open-ended approach.
With presently available open-ended baskets in which the wires of the basket form an open loop to provide a head-on retrieval, the basket wire is comprised of stainless steel, which is subject to kinking and does not have the desired resiliency for more than one stone capture.
With respect to large-sized stones, the overall size of the basket is also limited due to the tendency of the stainless steel wire to kink.